Bare metal surfaces are utilized in a variety of applications, such as the outer surfaces or skins of vehicles, including aircraft. Bare metal surfaces are polished for aesthetic and drag reduction purposes. Ascertaining the degree and quality of a metal polish has typically been performed by visual inspection, with the inspector relying on his or her experience and on reference samples containing various surface polishes. Thus, current visual polish inspections involve a substantial degree of subjectivity.
Panels manufactured and polished at different times, or by different processes or entities, may have different polish qualities and thus, look different from each other. Typically, clean polished metal surfaces present a uniform color when viewed from a position perpendicular to the surface, but often show variations in color or reflectivity when viewed from an angle if the degree of polish differs. In equipment where uniform polish is desired, such as with vehicles or fleets, uniformity of polish quality is important. By way of example, aircraft constructed with aluminum skin sections of differing degrees of polish can present an undesirable checkerboard or segmented look. In equipment manufactured in different segments, obtaining a uniform degree of polish across multiple segments may also be important. However, as previously stated, current visual inspection of polish for quality control and panel matching involves a substantial degree of subjective judgment by the visual inspector.
Therefore, there currently exists an unmet need in the art for a non-destructive, quantitative, and objective determination of quality of polishing on metal substrates.